Imagine you're a geologist who finds a fossil seashell on a mountaintop. You don't just catalog the shell — you reverse-engineer the ocean that made it. That's what Curiosity's science team is doing with disc-shaped inclusions found in Martian bedrock near the base of Mount Sharp. These features look like crystals, and if they are, their geometry and chemistry constrain the water temperature, salinity, and pH of the fluid that formed them. The 49th drill hole, called Nazca, is the instrument that cracks open the evidence. The campaign was methodical. Before drilling, the team ran a stability check on all six wheels to confirm solid footing, then a preload test pressing the drill bit against the rock to gauge whether the target block would hold. Only after both gates cleared did the drill fire. The target was chosen specifically for its abundance of disc-shaped features — this isn't a random sample but a deliberate return to a site flagged in earlier reconnaissance. Pre-drill analysis hit Nazca with three instruments: APXS for bulk elemental chemistry, MAHLI for close-up imaging, and ChemCam for laser-induced breakdown spectroscopy. Post-drill, ChemCam fired both passive spectral and active LIBS measurements into the tailings pile and down the drill hole wall itself — a depth profile that reveals whether surface weathering has altered the rock's composition relative to its interior. The drilled sample was delivered to CheMin, the X-ray diffraction instrument that will identify specific mineral phases. Those results were still in transit from Mars as of the planning date. The team isn't just drilling. Parallel observations targeted dark pebbles — specifically 'Palpala' and 'Puna' — which appear scattered across the area but don't all share the same composition. Understanding their origin matters because they could be transported fragments from different source rocks, offering a geological survey of materials Curiosity hasn't driven to. The constraint is physical: the ChemCam laser can move pebbles that are too small, so only sufficiently massive targets get measured. A second depth profile at the target 'Llama' tests whether compositional layering observed in an earlier LIBS profile is consistent across locations or locally variable. If consistent, it's a regional weathering signal. If variable, it's local heterogeneity. Meanwhile, 'Pacaya' targets the disc-shaped forms directly with LIBS, adding compositional data to the morphological observations that triggered the return visit. Long-distance Remote Micro-Imager observations focused on two buttes — Mishe Mokwa and Cordillera — that have drawn sustained interest for their sedimentary structures and textures. These are essentially natural cross-sections through layered deposits, and the team is building a visual library of their stratigraphy from multiple angles and distances. At Sol 5,050, Curiosity has been operating on Mars for nearly 14 Earth years, far beyond its original two-year primary mission. The 49th drill hole represents an extraordinary operational record, but more importantly, the science campaign around Nazca shows a team refining hypotheses in real time — returning to sites, running targeted comparisons, and using multiple instruments on the same features to triangulate environmental conditions that haven't existed on Mars for billions of years.
